"For nearly 22 years it has been my pleasure to have Tom Mockridge as a colleague," said News Corporation chairman and CEO Rupert Murdoch in a statement.

"Whether it was his early days with our newspaper group in Australia, his incredible work building Sky Italia, or his steadfast leadership of News International, Tom has always been a skilled executive and a trusted friend.

"His decision to step down is absolutely and entirely his own. I am sorry to see him leave us, but I know he will be a great success wherever he goes."

Mockridge - a previous chief executive of Sky Italia - was rumoured to be stepping down amid reports that he had been passed over for a new executive's position during restructuring of News Corporation.